package com.why.encrption;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Base64;
import android.view.View;
import android.widget.TextView;

import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

//非对称
//加密和解密两套密码
//为什么加密和解密不同密码
public class RSAActivity extends AppCompatActivity {

    private PrivateKey mPrivateKey;
    private PublicKey mPublicKey;
    private TextView showKeys;
    private byte[] mBase64Encode;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rsa);
        initView();
    }

    private void initView() {
        showKeys = (TextView) findViewById(R.id.showKeys);
    }

    //生成公钥和私钥
    public void generate(View view) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //1.获取公钥和私钥生成的对象
                    KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
                    //2.初始化,指定密码的长度bit
                    generator.initialize(1024);

                    //3.获取公钥和私钥
                    KeyPair keyPair = generator.generateKeyPair();
                    //3.1获取私钥
                    //私钥保存好了，私钥丢了，找不回来了
                    mPrivateKey = keyPair.getPrivate();
                    //3.2获取公钥
                    //公钥丢了，可以通过推导
                    mPublicKey = keyPair.getPublic();

                    //私钥的具体数据，私钥字节数组，保存该数据，文件中，sp
                    //！！！必须进行Base64转换
                    byte[] mPrivateKeyEncoded = mPrivateKey.getEncoded();

                    byte[] mPublicKeyEncoded = mPublicKey.getEncoded();

                    //对公钥和私钥中字节数组进行Base64编码
                    final byte[] privateKeyBase64Encode =
                            Base64.encode(mPrivateKeyEncoded, Base64.DEFAULT);

                    final byte[] publicKeyBase64Encode =
                            Base64.encode(mPublicKeyEncoded, Base64.DEFAULT);

                    //显示到文本框中
                    showKeys.post(new Runnable() {
                        @Override
                        public void run() {
                            showKeys.setText("私钥是："
                                    +"\n"+new String(privateKeyBase64Encode)+"\n"
                                    +"公钥是："+"\n"+new String(publicKeyBase64Encode));
                        }
                    });

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    //使用公钥和私钥进行加密解密
    public void encrypt(View view) {
        //使用私钥去加密，使用公钥进行解密
        //阿里巴巴----传给千峰，传文件
        //文件加密，私钥加密文件，传给千峰
        //千峰持有公钥，公钥进行解密
        String check = "100000000,123456";
        switch (view.getId()){
            case R.id.rsaEncrypt:
                try {
                    //1.初始化加密引擎
                    Cipher cipher = Cipher.getInstance("Rsa");
                    //2.初始化
                    if (mPrivateKey!=null){
                        cipher.init(Cipher.ENCRYPT_MODE, mPrivateKey);
                    }
                    //3.加密
                    byte[] doFinal = cipher.doFinal(check.getBytes());

                    mBase64Encode = Base64.encode(doFinal, Base64.DEFAULT);

                    showKeys.setText("RSA加密的数据是："+new String(mBase64Encode));

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (BadPaddingException e) {
                    e.printStackTrace();
                } catch (IllegalBlockSizeException e) {
                    e.printStackTrace();
                }

                break;
            case R.id.rsaDecrypt:
                try {
                    //1.初始化加密引擎
                    Cipher cipher = Cipher.getInstance("Rsa");
                    //2.初始化
                    if (mPrivateKey!=null){
                        cipher.init(Cipher.DECRYPT_MODE, mPublicKey);
                    }
                    //3.解密
                    byte[] base64Decode = Base64.decode(mBase64Encode, Base64.DEFAULT);

                    byte[] rsaDecode = cipher.doFinal(base64Decode);

                    showKeys.setText("RSA解密的数据是："+new String(rsaDecode));

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (BadPaddingException e) {
                    e.printStackTrace();
                } catch (IllegalBlockSizeException e) {
                    e.printStackTrace();
                }
                break;

        }
    }
}
